With increasing industrial development, diverse electronic appliances are used to achieve various purposes. An electronic appliance comprises a plurality of electronic components. Generally, different kinds of electronic components are operated by using different voltages.
As known, a power supply is essential for many electronic appliances such as personal computers, industrial computers, servers, communication products or network products. Usually, the user may simply plug a power supply into an AC wall outlet commonly found in most homes or offices so as to receive an AC voltage. The power supply will convert the AC voltage into different regulated DC output voltages for powering the electronic components contained in the electronic appliance. For example, the common DC output voltages include 12, 5 and 3.3 volts.
Conventionally, an electronic appliance has a mechanic switch element that is connected to a power conversion circuit. By switching the mechanic switch element, the output voltage of the power conversion circuit is selectively enabled or disabled and thus the electronic appliance is selectively enabled or disabled. For most electronic appliances, the power conversion circuit needs to offer a standby voltage to certain low-power circuit when the electronic appliance is powered off. The standby voltage is employed to achieve a certain function such as power status indication, time indication, data indication, an alarm clock function, subscription to initiation or remote control. In other words, the power conversion circuit outputs a first DC voltage and the standby voltage when the electronic appliance is powered on; and the power conversion circuit outputs the standby voltage when the electronic appliance is powered off.
Generally, the conventional power conversion circuit has two circuit loops for respectively outputting the first output voltage and the standby voltage. When the electronic appliance is powered on, the power conversion circuit simultaneously outputs the first DC voltage and the standby voltage. When the electronic appliance is powered off, the power conversion circuit only outputs the standby voltage to implement certain functions. Since the uses of two circuit loops need two transformers and two power control circuit, the overall volume of the power conversion circuit is bulky and the power density is insufficient. In addition, the power conversion circuit is not cost-effective.
There is a need of a providing a multi-output power conversion circuit to obviate the drawbacks encountered from the prior art.